Reinforced heat exchanger comprising a stack of plates

ABSTRACT

The heat exchanger ( 2 ) comprises a stack of plates ( 4 ) comprising a lower plate ( 20 ) onto which the other plates ( 22 ) are stacked. The heat exchanger ( 2 ) also comprises a fixation plate ( 6 ) and a reinforcement plate ( 8 ) between the fixation plate ( 6 ) and the lower plate ( 20 ). The reinforcement plate ( 8 ) has reinforcing elements ( 24 ) obtained from a cut and fold of the reinforcement plate ( 8 ) material.

In the field of heat exchangers for automotive vehicles, it is known touse heat exchangers comprising stack of plates for the circulation oftwo fluids alternately between the adjacent pairs of plates. Such heatexchangers are used for example as oil coolers for the oil of theengine. The oil and coolant circulate along respective sides of eachintermediate plate of the stack of plates.

The heat exchanger may also comprise a fixation plate for fixation ofthe stack of plates into the automotive vehicle. The stack of plates isfor example soldered to the fixation plate which is itself fastened tothe vehicle, for example with screws.

A reinforcement plate between the fixation plate and the stack of platesis also known from US2007084809-A and EP2267390-A.

However, these designs are costly and may still be improved in terms ofmechanical resistance.

An aspect of the invention relates to a heat exchanger comprising astack of plates comprising a lower plate onto which the other plates arestacked, and the heat exchanger also comprises a fixation plate and areinforcement plate between the fixation plate and the lower plate,wherein the fixation plate has reinforcing elements obtained from a cutand fold of the reinforcement plate material.

The reinforcing elements thus obtained bring reinforcement while stillallowing flexibility. Also, the process allows controlled position andshape of the reinforcing elements, with a reasonable cost.

It was also found that having reinforcing elements around only twocorners is optimal.

In particular embodiments, the heat exchanger may comprise one, severalor any combination of the following technical features:

-   -   the reinforcing elements are only one or more corners of the        lower plate. Having reinforcing elements only in one of more of        the corners bring reinforcement to the corners while also        providing more elasticity to the rest of the lower plate. It is        thus possible for the lower plate to follow slight deformations        where constraints are not critical, thereby relieving        constraints in the interface between the reinforcement plate and        the lower plate.    -   the reinforcing elements are only around two corners of the        lower plate;    -   for each reinforced corner, there is only one reinforcing        element;    -   the reinforcing elements are in contact with the lower plate;    -   the reinforcing elements have a shape complementary to the shape        of the lower plate;    -   the height h of the reinforcing element, measured from the top        planar surface of the fixation plate is preferably at least half        the height h′ of the peripheral edge of the lower plate,        measured from the top main planar surface of the reinforcement        plate;    -   the reinforcing elements have their internal surface following        the external surface of the lower plate;    -   the reinforcing elements are continuous around the respective        corners of the lower plate;    -   the reinforcement plate has only two reinforcing elements;    -   the reinforcement plate is a substantially planar plate;    -   the reinforcement plate is a planar plate, except in the regions        of the reinforcing elements;    -   the plate has two holes for the circulation of fluid, the        reinforcing elements being at proximity of the two holes;    -   the two holes are respectively for the inlet and outlet of a        fluid, in particular oil;    -   the lower plate has corresponding holes in regards of the two        holes for the circulation of fluid of the reinforcement plate,        the two holes of the lower plate being respectively in the two        corners of the lower plate that are reinforced by the        reinforcing elements;    -   the fixation plate has a planar surface receiving the fixation        plate and a protrusion around the reinforcement plate;    -   the protrusion is a peripheral edge of the fixation plate;    -   the peripheral edge is present along at least 50% of the contour        of the reinforcement plate;    -   the fixation plate has two holes for the circulation of fluid in        regards of the corresponding holes of the reinforcement plate;    -   the fixation plate has holes for fixation of the heat exchanger        into an automotive vehicle;    -   the reinforcement plate has holes for fixation in regards of the        corresponding holes of the reinforcement plate;    -   the stack of plates define two circuits for two respective        fluids, the circuits being configured so that the two fluids        circulate alternately between the adjacent pairs of plates;    -   each circuit flows along a respective side of each intermediate        plate of the stack of plates;    -   each intermediate plate of the stack of plates has holes for the        circulation of two fluids through each intermediate plate;    -   the lower plate has two holes respectively for the inlet and        outlet of one of the two fluids, in particular oil;    -   the end plate opposite to the lower plate has two holes        respectively for the inlet and outlet of the second of the two        fluids, in particular coolant;    -   the heat exchanger is an oil cooler.

Another aspect of the invention relates to a process for making a heatexchanger comprising a stack of plates comprising a lower plate ontowhich the other plates are stacked, the heat exchanger also comprising afixation plate, and a reinforcement plate between the fixation plate andthe lower plate, the fixation plate having reinforcing elements andwherein the process comprises actions of cutting and folding thereinforcing elements from the material of the reinforcement plate.

In particular embodiments, the process may comprise one, several or anycombination of the following characteristics:

-   -   the cutting and folding of a reinforcing element are made in a        single movement of a tool, in particular a cutting dye;    -   the cutting and folding are made in a single step;    -   all reinforcing elements made of the reinforcement plate made by        cutting and folding are made in a single step.

Embodiments of the invention will now be described, by way of example,with reference to the following drawings, in which:

FIG. 1 is a perspective view of a heat exchanger according to anembodiment of the invention, comprising a stack of plates, a fixationplate and a reinforcement plate between the fixation plate and the stackof plates;

FIG. 2 is a perspective view of the reinforcement plate present in theheat exchanger of FIG. 1;

FIG. 3 is a perspective view showing the fixation plate, thereinforcement plate and the lower plate of the stack of plates presentin the heat exchanger of FIG. 1, as well as on top of the lower plate,the first base plate of the stack of base plates;

FIG. 4 is a section view of the fixation plate, reinforcement plate andlower plate shown in FIG. 3.

FIG. 1 shows a heat exchanger 2 typically used for oil cooling. The heatexchanger comprises a stack of plates 4, a fixation plate 6 and areinforcement plate 8 between the fixation plate 6 and the stack ofplates 4.

The heat exchanger comprises a coolant inlet 10 and coolant outlet 12going through the top end plate 14 of the stack of plates. The coolantis for example a water and glycol based liquid commonly used for enginecooling. On FIGS. 2 & 3, an oil inlet 16 and an oil outlet 18 can alsobe seen through the lower plate 20 of the stack of plates 4, through thereinforcement plate 8 and through the fixation plate 6. The heatexchanger is thus intended to be used as an oil cooler, for example forcooling the oil of the engine of the automotive vehicle. However, theheat exchanger could also be used for heat exchange between otherfluids, such as for example between water and glycol based liquid and arefrigerant such as for example 1234yf.

The stack of plates 4 of the heat exchanger is designed so that the twofluids circulate alternately between the adjacent pairs of plates. Thatis to say, each fluid circulates along respective sides of eachintermediate plate 22 (also called “base plates”) of the stack of plates4. The base plates 22 have holes for the circulation of the two fluidsthrough each plate.

This type of stack of plates 4 is commonly used and known to the personskilled in the art.

The reinforcement plate 8 shown more specifically on FIGS. 2 a 3, is asubstantially planar plate having two reinforcing elements 24 around twocorners 26 of the lower plate 20. These two reinforcing elements 24shown more closely on FIG. 4 are obtained by cutting and foldingmaterial from the reinforcement plate.

As show on FIG. 4, the internal surface 28 of the reinforcing elements24 contact the external surface 30 of the peripheral edge 32 of thelower plate 20. Preferably, the internal surface 28 of the reinforcingelements 24 have a shape that is complementary of the shape of theexternal surface 30 and thus in contact along the whole corner 26.

The height h of the reinforcing element 24, measured from the top planarsurface 34 of the fixation plate 6 is preferably at least half theheight h′ of the peripheral edge 32 of the lower plate 20, measured fromthe top main planar surface 36 of the reinforcement plate 8.

The cutting and folding of a reinforcing element 24 are made preferablyin a single movement of a cutting dye or any other adapted tool.Alternatively though, it is possible to make it in two steps with twodifferent tools/apparatus. All reinforcing elements 24 of thereinforcement plate 8 made by cutting and folding are preferably made ina single step.

Preferably, there are reinforcing elements 24 around only two corners 26of the lower plate 20, as can be seen on the figures. Alternatively,there could be four reinforcing elements 24 around each corner 26 of thelower plate 20 but this is a less preferred solution.

Preferably also, the reinforcing elements 24 are in one part (or“continuous”) around their respective corners 26. That is to say thateach corner 26 is reinforced by only one reinforcing element. It wasfound a more reliable reinforcement compared to having severalreinforcing elements around a specific corner.

Preferably again, the reinforced corners are the one at proximity of theholes for fluid communication 16 and 18 for oil. If the inlet and outletof water and glycol based coolant were also designed through thereinforcement plate 8 and fixation plate 6, which is also a possiblealternative, then the reinforcing elements would be at proximity of theinlet & outlet for oil, and there would be no reinforcing elements atproximity of the inlet & outlet for water & glycol based coolant.

The reinforcement plate 8 has fixation holes 38 in regards ofcorresponding fixation holes of the fixation plate 6, in order toreceive for example fixation screws intended to fasten the heatexchanger into the automotive vehicle. Alternatively, the reinforcementplate has no fixation hole and the fixation plate 6 is fastened to theautomotive by holes that are external to the reinforcement plate.

The reinforcement plate 8 also has positioning protrusions 42, or moregenerally positioning elements, that cooperate with correspondingpositioning elements 42 of the lower plate 20. In this specific example,the positioning elements 42 of the lower plate 20, the reinforcementplate 8 and the fixation plate 6, are protruding plots, the protrudingplots of each of the plates 20, 6 and 8 being respectively identical.

The fixation plate 6 shown on FIGS. 2, 3 & 4 is intended to receive thereinforcement plate and to fasten the heat exchanger 2 to the automotivevehicle thanks to fixation holes 44 in regards of the fixation holes 38of the reinforcement plate 8. Fixation can be done with fixation screwsor any other adapted fixation element such as bolts.

The fixation plate 6 has a top planar surface 34 (FIG. 4) receiving thebottom planar surface 46 of the reinforcement plate, the two surfacesbeing in contact with each other. Alternatively, the fixation plate 6and reinforcement plate 8 could have any other adapted geometry.

The fixation plate 6 has a peripheral edge 48 around the reinforcementplate 8 for reinforcement of the fixation plate 6.

Preferably, the peripheral edge 48 extends along substantially the wholecontour of the reinforcement plate 6. In the figures, there are only tworegions 52 where the peripheral edge 48 is not present, but theperipheral edge 48 is still present around at least 50% of the contourof the reinforcement plate 6.

At last, the stack of plates 4 is made of identical base plates, anupper plate (not shown) and of the top end plate 14, as commonly known.

As shown on FIG. 3, the lower plate 20, has two holes 54 & 56. Thereholes are inactive for the lower plate 20 because these holes do nothave corresponding holes in the reinforcement plate 8 and in thefixation plate 6.

The lower plate 20 also has holes 58 & 60 for the circulation of oil.

The base plates 22 are all identical. They have holes 62 for thecirculation of oil and holes 64 for the circulation of coolant.

Also, each base plate is turned 180 degrees in respect of the adjacentbase plates. In this way, it is not necessary to make two differentkinds of plates, as commonly known.

A first group of base plates are intended for the circulation of oilabove the base plates 22. The holes 62 for the circulation of oil are inthe same plane as the main planar surfaces of these plates and the holes66 for the circulation of coolant are elevated so that they make a tightcontact with the bottom planar surface of the base plate above, which isturned 180 degrees.

The second half of the base plates 22 of the stack of plates have holes64 for coolant in the plane of the main planar surfaces of these baseplates 22 and the holes for the circulation of oil 62 are elevated sothat they make a tight contact with the bottom surface of the platesabove. Coolant will circulate on the top side of this second type ofbase plate.

Importantly, each base plate 22 of the stack of plates 4, the lowerplate 22 and the upper plate (not shown) having a peripheral edge 32 ofan identical shape. The peripheral edge 32 of each plate receives theexternal surface of the peripheral edge 32 of the plate above in a tightmanner. This design is also called a “tub” design wherein each tub platereceives the tub plate above in a tight manner along the peripheraledges 32.

The top end plate only has holes 66 & 68 for receiving the inlet &outlet of coolant. Alternatively, as explained above, the inlet & outletof coolant could also be on the side of the fixation plate 6, in whichcase, there would be not circulation holes in the top end plate 14.

1. A heat exchanger comprising: a stack of plates comprising a lowerplate onto which the other plates are stacked; a fixation plate; and areinforcement plate between the fixation plate and the lower plate,wherein the reinforcement plate has reinforcing elements obtained from acut and fold of the reinforcement plate material.
 2. The heat exchangeraccording to claim 1, wherein the reinforcing elements are only aroundone or more corners of the lower plate.
 3. The heat exchanger accordingto claim 1, wherein the reinforcing elements are only around two cornersof the lower plate.
 4. The heat exchanger according to claim 1, whereinthe reinforcing elements are in contact with the lower plate.
 5. Theheat exchanger according to claim 1, wherein the reinforcing elementshave a shape complementary to the shape of the lower plate.
 6. The heatexchanger according to claim 1, wherein the reinforcement plate is asubstantially planar plate.
 7. The heat exchanger according to claim 1,wherein the reinforcement plate has two holes for the circulation offluid, the reinforcing elements being at proximity of the two holes. 8.The heat exchanger according to claim 7, wherein the lower plate hascorresponding holes in regards of the two holes for the circulation offluid of the reinforcement plate, the two holes of the lower plate beingrespectively in the two corners of the lower plate that are reinforcedby the reinforcing elements.
 9. The heat exchanger according to claim 1,wherein the fixation plate has a planar surface receiving thereinforcement plate and a protrusion around the reinforcement plate. 10.The heat exchanger according to claim 8, wherein the protrusion is aperipheral edge of the fixation plate.
 11. The heat exchanger accordingto claim 1, wherein the stack of plates define two circuits for tworespective fluids, the circuits being configured so that the two fluidscirculate alternately between the adjacent pairs of plates.
 12. The heatexchanger according to claim 1, wherein the heat exchanger is an oilcooler.
 13. A process for making a heat exchanger, the heat exchangercomprising: a stack of plates comprising a lower plate onto which theother plates are stacked, the heat exchanger comprising a fixationplate, and a reinforcement plate between the fixation plate and thelower plate, the fixation plate having reinforcing elements and theprocess comprising: cutting and folding the reinforcing elements fromthe material of the reinforcement plate.
 14. The process according toclaim 1, wherein the cutting and folding of each reinforcing element aremade in a single movement of a tool.